Google, Facebook, Twitter: Not Enough Dollars to Go Around

Given the size of the ad market, it will be nearly impossible for dot-coms to all grow into their market values.

Google, Facebook, Twitter, and a slew of other high-flying dot-coms are headed for a pie problem. Viewed individually, each seems to have endless potential to turn popular, free services into more revenue by grabbing a larger slice of the online advertising pie. But as a whole, online ad spending is growing at a fairly predictable pace, and won't be large enough anytime soon to justify all of the high-flying valuations on dot-com shares.